"One of the major social policy issues facing the U.S. in the first decade of the 21st century is the large number of Americans lacking health insurance. This article surveys the major economic issues around covering the uninsured. I review the facts on insurance coverage and the nature of the uninsured; focus on explanations for why the U.S. has such a large, and growing, uninsured population; and discuss why we should care if individuals are uninsured. I then focus on policy options to address the problem of the uninsured, beginning with a discussion of the key issues and available evidence, and then turning to estimates from a micro-simulation model of the impact of alternative interventions to increase insurance coverage"--National Bureau of Economic Research web site.